The Fundamental Plane Relation Of Early-type Galaxies In Sloan Digital Sky Survey: Environmental Dependence

Using the data from SDSS DR7 and SDSS group catalog,we study the environ-mental dependence of the fundamental plane(FP),the stellar mass fundamental plane(FP*)and the mass plane(MP).We select a sample with 70,793 early-type galaxies from SDSS DR7.With the help of the galaxy group catalogue based on SDSS DR7,we define the environmental parameters for each galaxy in the sample as the halo mass and whether it is a central or satellite galaxy.By studying the features of the FP,the FP*and the MP in different environments,we investigate the effect of different environmental processes on the galaxy property and the origin of the FP tilt.In Chapter 2,we investigate the environmental dependence of the FP.Firstly,we introduce the selcetion criteria of the early-type galaxy sample and SDSS group catalog used in this work.Next,we introduce the fitting method of the FP.Then we calculate the FPs in different dark matter halo mass bins for central and satellite galaxies respectively.We find the environmental dependence of the FP coefficients are similar in g,r,i and z bands.The environmental dependence for central and satellite galaxies is significantly different.While the FP coefficients of centrals vary systematically with the halo mass,those of satellites are similar in different halo mass bins.The discrepancy between centrals and satellites are significant in small halos,but negligible in the largest halo mass bins.These results remain the same when we only keep red galaxies,or galaxies with b/a>0.6,or galaxies in a specific radius range in the sample.After the correction of the sky background,results are still similar.In Chapter 3,we replace the surface brightness into the stellar mass surface density to calculate the FP*.Then we calculate FP,coefficients of galaxies in different envi-ronments and compare them with those of the FP to study the contribution of the stellar population.We find that coefficient a of the FP*is systematically larger than that of the FP,but coefficient b of the FP*is similar to the FP.Moreover,the environmental dependence of the FP*is similar to that of the FP.For central galaxies,FP*coefficients are significantly dependent on the halo mass.For satellite galaxies,the correlation be-tween FP*coefficients and the halo mass is weak.We conclude that the tilt of the FP is not primarily driven by the stellar population.In Chapter 4,we replace the surface brightness into the stellar mass surface den-sity to calculate the MP,and study the relation between MP coefficents and the radius from the center of the dark matter halo for three central early-type galaxy samples.For central early-type galaxies without satellite galaxy and in small halos(G1),we find that the coefficients of the MP tend to be constant and are close to the virial relation as the radius from the halo center is larger than 50 times effective radius of central galaxies.At small radius,the tidal force of the halo makes the MP deviate from the virial re-lation.For central early-type galaxies without satellite galaxy and in the large halos(G2),coefficient a is remarkably different from the virial relation.This is because of the low-luminosity satellite galaxies in large halos which are not observed due to the flux limit.For central early-type galaxies with satellite galaxies and in the large halos(G3),coefficent a is even larger than G2 sample.This verifies that the satellite galaxies contribute significantly to the MP.